Construction of an immunosensor based on Cys/Au@TiO2 modification for the detection of liver cancer marker PIVKA-II

An ultrasensitive immunosensor of Cys/Au@TiO 2 based on disposable screen-printed electrodes (SPE) for PIVKA-II detection for hepatocellular carcinoma (HCC) diagnosis was developed by utilizing Cystine (Cys) and nanocomposite Au@TiO 2 . Firstly, HAuCl 4 underwent a reduction reaction with NaBH 4 , then Au nanoparticles were coated onto TiO 2 nanoparticles. Followed, Cys/Au@TiO 2 was formed through self-assembly of cysteine to allow the monoclonal antibody of abnormal thrombospondin to bound to the amino group on the surface of the composite by covalent bonding. The mechanism is to determine the changes in the current of the sensor caused by the specific binding of the abnormal prothrombin monoclonal antibody adsorbed by the complex with its antigen. The Cys/Au@TiO 2 immunosensor was fully characterized by various analytical approaches and it showed a wide linear testing range of 1–10000 pg mL −1 (R 2  = 0.991) and the limit of detection down to 0.77 pg ml −1 , with highly sensitivity and specificity. The results showed that the developed immunosensor platform can effectively detect trace amounts of PIVKA-II protein and has potent clinical application for HCC diagnosis.